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Possible RAID Implementation


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#1
Troy

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Hi guys,

I got a question myself... :)

In case you're wondering, my rig is in my profile. :)

I have 2x 250GB Seagate hard drives, one for everything, one for backups. I'm considering grabbing another one (as they're cheap) and also a RAID hardware card to run a RAID 5 configuration. My key consideration for this possible upgrade is data redundancy. I don't care about if it's faster or not, just if I have a failure of some sort I can replace a drive and have it rebuild it for me.

Does this sound right? Should I grab another 2x 250GB drives, or a different RAID configuration (like RAID 10 or...)?

Also, what RAID card should I get? I seem to have this impression that Adaptec are good, but I can't find many on local sites.

Here are some of the sites I can purchase from:

http://www.umart.com.au (Gold Coast store, preferably)
http://www.gamedude.com.au
http://www.auspcmarket.com.au
http://www.qcgo.com.au/ashmore

If you can find a good card somewhere else that will post it, I'd consider it too. I want good quality, of course, but I'd like to keep this as cheap as possible. If it becomes too expensive and you wouldn't recommend anything cheaper, I won't do it.

What about this card?

I appreciate anybody's comments with experience in this area.

Cheers

Troy
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#2
Neil Jones

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RAID for home use, in my own personal opinion, is just not needed.
For backup purposes, an external hard disk drive that you plug in manually and copy either the important stuff to at regular intervals to it, or clone the entire drive to it, again at regular intervals, will be more than adequate.

Also don't forget, touch wood, that if your computer should ever be stolen, your RAID backup will go with it. An external drive you won't have that problem.

If you want a backup solution as cheap as possible, forget RAID altogether and buy yourself an external drive. Okay you'll have to get into the rigmarole of cloning the drive to it regularly but you can clone it all back manually as and when the hard drive falls over.
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#3
Troy

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Hi there,

RAID for home use, in my own personal opinion, is just not needed.

Also don't forget, touch wood, that if your computer should ever be stolen, your RAID backup will go with it. An external drive you won't have that problem.

I don't necessarily want a "backup" solution, I already have backups planned and I do them regularly. It's more the "geek" in me that wants to do this. I do realise this is very overkill for a home computer! :)

I still will be running backups, as well as the RAID implementation.

And don't forget, it's possible that the thieves just might take the external drive as well. :)

Cheers for your input though.

Troy
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#4
dsenette

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i would agree with neil that raid is ridiculous in a home environment...and that goes for any level of True RAID (0 doesn't count in my opinion....)...however if you're really just wanting to play with stuff...then that's your right

a few notes on raid5....the drives (at least per my research) have to all be of the same size...you can't have 2 40 gig drives and 1 120 gig drive and have raid5 work...another note is that you can't just instate raid5 (or any of the higher level redundant raid levels)....you have to start from scratch...which would mean you'd have to reinstall windows etc.. after the array was built
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#5
Neil Jones

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And don't forget, it's possible that the thieves just might take the external drive as well. :)


Then perhaps you should keep your external backup away from the computer, otherwise it defeats the whole point of a backup system in the first place. It's like locking the day's takings for a company in the company safe and then leaving the keys on the desk all night.

But anyway...

RAID 1 is supposedly the more secure option if you do want a RAID setup because its basically a mirror image, and some implementations of this will rebuild it for you as well - this is specified with redundancy built into it.
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#6
Troy

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a few notes on raid5....the drives (at least per my research) have to all be of the same size...you can't have 2 40 gig drives and 1 120 gig drive and have raid5 work...another note is that you can't just instate raid5 (or any of the higher level redundant raid levels)....you have to start from scratch...which would mean you'd have to reinstall windows etc.. after the array was built

Hi dsenette,

I understand they all have to be the same. Currently I have 2x 250GB 7200.10 Seagate hard drives, and I am able to purchase more of the exact model drives for what I believe to be rather cheap.

I also understand that once the RAID is achieved, I would then need to install Windows and move everything back on to the drives again. I see no reason why I won't be able to make a full backup, and then "restore" the backup onto the RAID drives once everything's setup?

So what's your opinion on which RAID variant to go, anyway? Would RAID 5 be a good option? I am open to other ideas if I can find a recommended quality RAID card at a good price for my budget. Something that will be for the geek in me to triumph over!

Windows should see it as just a large hard drive, right? Maybe it's a bit more technical than that (like Windows knowing there's x drives in a RAID setup under Disk Management or something), but under Computer it will report one drive?

It would be good if I could check out somebody's RAID setup already to get a better idea on it.

*troy wanders off to the local university... :)

RAID 1 is supposedly the more secure option if you do want a RAID setup because its basically a mirror image, and some implementations of this will rebuild it for you as well - this is specified with redundancy built into it.

Hi Neil,

RAID 1 is not an option in my opinion. I don't want to have two hard drives doing exactly the same thing. While this would be a redundancy option, I don't like that you've got two hard drives for only one hard drive's space. I might as well run RAID 1 from my motherboard RAID options. :)

Or am I wrong in thinking that 4x 250GB drives in RAID 5 will give me (give or take) 1TB of disk space?

And what did you mean by some implementations will rebuild it? If one drive dies, then shouldn't you be able to add another drive and have it rebuilt by all implementations? If it's RAID 1, then you'll still be able to access your stuff with only one drive (right?), but then you'd have to back the whole lot up elsewhere and then format the original and the new one to a RAID 1 solution again. Sounds dodgy... :)

Many thanks for your responses, though. This is rather interesting, even if I end up doing nothing about it... I'm definitely going to do some more research on it, anyway. Got any known good links you recommend? Of course I'll be checking "Google"!

Cheers

Troy

P.S. Yeah yeah yeah, I know this is way overkill! You don't need to mention that again... :)
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#7
james_8970

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I'm going to start of by warning you and stating that you shouldn't get into RAID. RAID is similar to watercooling, either go all out or go home. Don't skimp out.

Currently I have 2x 250GB 7200.10 Seagate hard drives, and I am able to purchase more of the exact model drives for what I believe to be rather cheap.

You need at least 3 drives for RAID 5.

So what's your opinion on which RAID variant to go, anyway? Would RAID 5 be a good option?

I'm not sure about anyone else, but I'm only going to recommend RAID5. Warning, you're going to suffer a major performance hit when it comes to writing speeds.

Windows should see it as just a large hard drive, right?

Yes, basically.

Or am I wrong in thinking that 4x 250GB drives in RAID 5 will give me (give or take) 1TB of disk space?

You lose ~14% from what I've seen. I strongly encourage you to buy all the drives at once, it's best that the firmware of all the hard drives are the same.

If one drive dies, then shouldn't you be able to add another drive and have it rebuilt by all implementations? If it's RAID 1, then you'll still be able to access your stuff with only one drive (right?), but then you'd have to back the whole lot up elsewhere and then format the original and the new one to a RAID 1 solution again.

Unless you know how to rebuild a RAID array, DO NOT produce a RAID array, period. I don't know much about rebuilding RAID arrays which is why I haven't fooled around with it yet. I also feel the it's not worth the performance hit, I'll gladly drag a drop files every now and then from internal hard drive to another internal hard drive if I'll have writing performance hit that is 20%. I have to admit, with 500GB+ drives it becomes a mess of old files, but it's an inconvenience I'm willing to accept.

I also understand that once the RAID is achieved, I would then need to install Windows and move everything back on to the drives again.

DO NOT put your OS onto your RAID array. Look at it this way, if your OS becomes corrupt, reinstalling windows all of the sudden becomes a huge chore and puts all the data on you array at risk. I personally would have a hotswappable drive if I ever created a RAID array, but it's an additional cost.

Yeah yeah yeah, I know this is way overkill! You don't need to mention that again...

Wouldn't call it overkill, just unnecessary.

James

Edited by james_8970, 22 April 2008 - 10:08 PM.

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#8
Troy

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Hi James,

Yes I understand that it's not worth it unless I can grab good-quality components. That's why I intend to choose a hardware-based solution and not just any old brand, either. Unfortunately, nobody has contributed to comment about whether Adaptec is a good manufacturer, or if there are others I should consider also.

As you can see in the first post, I know I have to have minimum 3 drives to run RAID 5.

You say that it's best if the firmwares are all the same on each drive - how do you know this? Even so, it's a bit hit-and-miss to suggest that purchasing the hard drives all at once will give me the same firmwares... One drive may have been sitting on the shelf for so many weeks and two drives may have been a recent delivery to the shop, for example. Similar kind of scenario to ordering 5 motherboards to find I have a few different revisions of each... (Except you can update a firmware).

Cheers

Troy
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#9
dsenette

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the firmware issue should be irrelevant...as far as getting them the same at the time of purchase...if you get the same model of drive for all three...you can just update the firmware on them and you'd be fine

to my knowledge the only levels of raid that will rebuild are those that use parity...which i think starts at 3? i can never remember off hand......that's the point of the parity info...to rebuild a drive in the array if one goes down....

in raid 3 and 4 if any drive OTHER than the one containing the parity info goes down...you can rebuild the array automatically.....if the parity drive goes down.....i THINK (but have never tested) that the parity would rebuild itself from the other two drives as long as you don't lose one of the other drives in the process

with raid5 the parity is distributed...so you can lose any single drive and it will rebuild itself....if you lose two drives you're toasted....raid6 does double distributed so you could in theory lose 2 drives out of the stack and still rebuild the array


DO NOT put your OS onto your RAID array. Look at it this way, if your OS becomes corrupt, reinstalling windows all of the sudden becomes a huge chore and puts all the data on you array at risk. I personally would have a hotswappable drive if I ever created a RAID array, but it's an additional cost.

i disagree with this whole heartedly....you can (and most servers do) put the OS on the raid stack.....once you build the array...you're presented with a single logical volume...which you can partition however you like from there.....which also gives your OS redundancy etc...i don't disagree with hotswap...it's great for raid setups...
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#10
Troy

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if you lose two drives you're toasted

Now that I think of it, I had a friend who lost two drives from a RAID 5 implementation... All his business data was on it (and no backups) and he spent 36 hours straight before managing to get Acronis to backup his data to... a few hundred CD's... (it was all he had lying around at 2.00AM when he finally got it working). :)

I don't know how he did it, I should ask him sometime. It blew his mind, though, and he spent like 2 days in bed after it happened! Come to think of it, I might ask him what controller he recommends for me, the more opinions the better.

Anyway, does RAID 5 with 3 hard drives allow hotswapping, or is that with 4 drives or... :)

So you'd recommend setting up two partitions on a RAID 5 setup, one for Vista and one for data? Or one for Vista and the other for... Vista? How do I get OS redundancy? You lost me there.

Cheers

Troy
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#11
dsenette

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Anyway, does RAID 5 with 3 hard drives allow hotswapping, or is that with 4 drives or...

hot swapping is dependent on your drive controller and drives not raid or amount of drives...you would have to have a hotswappable system for it to work..i.e. hot swap sata drives/controllers or hot swap IDE

So you'd recommend setting up two partitions on a RAID 5 setup, one for Vista and one for data? Or one for Vista and the other for... Vista? How do I get OS redundancy? You lost me there.

you get OS redundancy on the physical level....as in if a drive craps out it will rebuild itself....you don't get a second fail over OS in case of a software issue.....you can partition the logical volume however you like
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#12
Troy

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hot swapping is dependent on your drive controller and drives not raid or amount of drives...you would have to have a hotswappable system for it to work..i.e. hot swap sata drives/controllers or hot swap IDE


Hi there,

This sounds really good. Any products you know of that would be good for this setup in my intended application?

Cheers

Troy
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#13
dsenette

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i'm definitely not a hardware geek....google hot swappable raid or something to that effect....i've found a few sata enclosures that are built for hot swapping and come with raid controllers built in etc....i've never used them as the only raid systems i use are in my servers that come with this stuff built in
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#14
Troy

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Hi again,

So the servers you have come with hardware solutions already built in? Interesting, I don't know too much about server hardware at the moment, other than the Tech Academy build we're doing at the moment, which is a very different type of server to the ones you're talking about, I would imagine.

I've found a few SATA RAID enclosures, they're pretty expensive and definitely above my budget! :) But they do look cool. :)

I can't really find much of anything what I'm looking for...

A good quality SATA RAID card that has 4 ports and supports RAID 5 - aimed at the SOHO market... Oh and supports hotswapping would be nice. :)

Cheers

Troy
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#15
dsenette

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for your use...hot swapping is not needed....hot swapping is for mission critical devices that can't ever be turned off (like my file servers and my domain controllers etc...)....in a mission critical system....you use hot swap equipment so you can just pop a new drive in without turning the server off.....in your scenario.....if one of your drives physically dies....you can turn your pc off and put in a new drive....it's not like you're going to have a tray of these drives sitting around to swap with anyway....if one of your drives dies...you'll have to wait for it to get shipped anyway
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